Comparison of total column ozone obtained by the IASI-MetOp satellite with ground-based and OMI satellite observations in the southern tropics and subtropics

摘要

This paper presents comparison results of the total column ozone (TCO) dataproduct over 13 southern tropical and subtropical sites recorded from theInfrared Atmospheric Sounder Interferometer (IASI) onboard the EUMETSAT(European organization for the exploitation of METeorological SATellite)MetOp (Meteorological Operational satellite program) satellite. TCO monthlyaverages obtained from IASI between June 2008 and December 2012 are comparedwith collocated TCO measurements from the Ozone Monitoring Instrument (OMI) on theOMI/Aura satellite and the Dobson and SAOZ (Système d'Analyse parObservation Zénithale) ground-based instruments. The results show thatIASI displays a positive bias with an average less than 2 % with respectto OMI and Dobson observations, but exhibits a negative bias compared toSAOZ over Bauru with a bias around 2.63 %. There is a good agreementbetween IASI and the other instruments, especially from 15° Ssouthward where a correlation coefficient higher than 0.87 is found. IASIexhibits a seasonal dependence, with an upward trend in autumn and a downwardtrend during spring, especially before September 2010. After September 2010,the autumn seasonal bias is considerably reduced due to changes madeto the retrieval algorithm of the IASI level 2 (L2) product.The L2 product released after August (L2 O₃ version 5 (v5)) matchesTCO from the other instruments better compared to version 4 (v4),which was released between June 2008 and August 2010. IASI bias errorrecorded from September 2010 is estimated to be at 1.5 % with respect toOMI and less than ±1 % with respect to the other ground-basedinstruments. Thus, the improvement made by O₃ L2 version 5 (v5)product compared with version 4 (v4), allows IASI TCO products to be used withconfidence to study the distribution and interannual variability of totalozone in the southern tropics and subtropics.